Most earth moving equipment vehicles such as bulldozers generally include a chassis, a form of earth working tooling, driver cabin, and a form of access or access system. The chassis includes all the mechanical parts that form the structural frame of the earth moving equipment vehicle. The driver operates the earth moving equipment vehicle from the driver cabin. The access system provides access between the ground level and the cabin.
Retractable access systems of different configurations are presently known and have two final positions namely the deployed position and the retracted position. The major types of access devices are the vertical variable height access system and the swing access system.
The vertical variable height access system would generally be used for large excavators and large earth moving equipment. In the vertical variable height access system, the ladder or stairs would be operated vertically and would remain vertical both in the deployed position and retracted position.
In a swing access system the ladder or stairs when operated will swing up or down to reach either the retracted position or deployed position respectively. The basic constituents of any access system include a ladder or stairs and a retraction mechanism to actuate the ladder or stairs. The ladder is generally pivoted on one or two points on the earth moving equipment. The retraction mechanism moves the ladder or stairs between the deployed position and the retracted position. The retraction mechanism is usually actuated by mechanical means, electrical means or hydraulic means.
When in use, the earth moving equipment travels over rough surfaces. Such travel over rough surfaces causes shocks and vibrations to the chassis of the earth moving equipment. These shocks and vibrations are transferred to all on-board components including the access system.
For safety reasons, the ladder of a swing access system is retracted before the earth moving equipment is set in motion. Due to the shocks and vibrations acting on the ladder, the ladder experiences “bounce” i.e. sudden jerky movements. The bounce is amplified at the unattached end of the ladder due to the overhang of the ladder. The bounce is undesirable because it damages the pivot joints of the ladder to the earth moving equipment, any item that the bouncing ladder comes in contact with, and the ladder itself. Prolonged bouncing movement could lead to failure of certain components which are adversely affected by the bounce. The bounce also creates noise which may distract the driver/operator of the earthmoving equipment.
It is an object of the present invention to reduce ‘bounce’ of a retracted ladder of an access system when the earth moving equipment is travelling.